Process of making fermented sour doughs

ABSTRACT

The invention concerns fermented sour doughs, comprising starter material, ground cereal kernels or grains, balance water that contain maximum 32 wt % of water and display a pH &lt;4.2. The titratable acidity of the doughs is at least 25, the weight ratio lactic acid: acetic acid of the doughs is &lt;3.0. The doughs can contain salt and can be mixed with a pre-dried flour with water content 1-5 wt %. Part of the invention is also a process for the preparation of the fermented sour doughs.

This is a Divisional application of Ser. No. 08/087,588 filed Jul. 6,1993, now abandoned.

Fermented sour doughs for the preparation of e.g. Rye-breads are knownfor quite a long time. Those known doughs, however, always containconsiderable amounts of water such as about 50 wt %. It was believedthat such an amount of water was necessary in order to enable the sourstarter material present in those doughs to be active and to producelactic acid and acetic acid in the dough upon fermentation.

Moreover, fermented sour dough powders were produced by making a doughwith a high water content and removing water from this dough byfreeze-drying, spray-drying and/or heating. However, freeze-drying underdecreased pressure, spray-drying and/or heating of the dough wasdetrimental for the flavour content of the dough; as flavor componentsare often volatile components such as esters or acetic acid.

We have found a solution for the problems mentioned above, whereas wefurther have developed a fermented sour-dough composition with arelatively low water content, wherein during fermentation the startermaterial was active and produced free acid, such as lactic acid andacetic acid.

Therefore, our invention concerns in the first place a fermented sourdough composition, comprising at least sour starter material (orinoculum), ground cereal kernels or grains, which will be called flourfrom hereon for sake of convenience and optionally bran and balancewater, which dough is characterized by the presence of maximum 32 wt %,preferably 25-32 wt %, in particular 28-30 wt % of water and a pH ofless than 4.2, preferably less than 4.0, in particular 3.6-4.0.

The amounts of acids that are required in the dough composition dependvery much on the nature of the cereal flour that is used. Suitableflours that can be applied are e.g. Rye, wheat, barley, either per se ormalted or mixtures thereof. Also triticale, a grain obtained bybiogenetical engineering is advantageously applied. The amount of acidthat is produced in the sour dough depends on the kind of cereal flourthat is used, preferably the titratable acidity of the dough is at least25 (defined according to Standard-Methoden fur Getreide, Mehl und Brot,6. Erw. Auflage, Detmold 1978, p- 106-107). This titratable acidity isin particular more than 30 when a whole Rye meal is used in the dough,whereas a value of more than 50, in particular more than 55 is requiredwhen a Rye-bran is applied. Interpolated data should be applied whenmixtures of meal and bran are used.

Whereas the weight ratio of lactic acid to acetic acid in sour doughsobtained after freeze drying, spray-drying and/or heating is in generalabove 3.0, those ratios are in fermented sour doughs of the inventionless than 3.0.

As our dough compositions contain about 25-32 wt % of water it cannot beexcluded that some moulds can develop in our doughs. Still the productsmade from the doughs according to our invention can display a shelf liveof at least 6 months. This long shelf live is in particular obtainedwhen we incorporate 2-8 wt % of an organic or inorganic salt, e.g.Na-acetate, Ca-acetate, Ca-propionate, Ca-citrate, KCl and in particularNaCl in our doughs. The presence of those salts results in a lower wateractivity of the sour dough, of course the ratio lactic acid:acetic acidis not affected by the presence of such salts.

Another very convenient aspect of our invention is, that we can make afree flowing fermented sour dough with a water level of 20-25 wt %. Thiscan be achieved by mixing of the fermented dough according to theinvention with 20-38 wt % (on weight of the total mixture) of a driedflour with a water content of 1-5 wt %.

Any dried flour can be used, very useful, however, is when an extruded,gelatinised cereal flour is added to our sour dough system. Very goodsour dough compositions, which combine all desired properties, such asfree-flowing, free of moulds, long shelf live and having the desiredratios latic acid:acetic acid have the following composition:

60-70 wt % of the sour dough with less than 32 wt % of water and pH <4.2

2-8 wt % of a water activity decreasing salt

22-38 wt % of the dried flour with a water content of 1-5 wt %

which dough compositions display an overall water content of 20-25 wt %,and preferably have a lactic acid to acetic acid weight ratio of lessthan 3.0.

Of course the sour doughs according to the invention and the productsmade from them can also contain the usual dough or bread improvercomponents. Those components are e.g. sugar, saccharose, water-freeglucose, lactose, whey-powder, emulsifiers, enzymes, yeasts etc.

The dough compositions can be used in order to make bakery products fromthem, in particular breads. Therefore, also the bakery products andbreads which can be obtained after baking of compositions containing oursour doughs are also part of the invention.

According to EP 339 750 a dried form of a leavening barm is producedthat comprises viable cells of a maltose-fermenting lactobacillus andviable cells of a non-maltose fermenting Saccharomyces, whole grainflour and 5-12 wt % water. Essential is that a symbiotic mixture ofmaltose-fermenting and non-maltose fermenting microorganisms is applied,as according to page 4, lines 30-34 of this EP in this way thecomposition is distinguishable from sour dough starters. The dryingprocess is very complicated and proceeds in multi-steps by the additionof flour (water content: ca. 12%) and water, followed by fermentationuntil a water content of about 28% is obtained (cf. example I). Thisproduct is subjected to a short fermentation: 28 hrs. The last drying tothe required water content of 5-12% is performed by using a draft of airof about 65° C. (cf. example 1). The pH of the product is very low(about 3.5) in order to achieve self-preservative character.

Our product and process are different from above prior art, because inour products a sour starter material is present and not a barm, thewater level is higher, the pH is higher, while we apply a pre-driedflour with a water content of 1-5 wt % instead of an air drying process.Our process, therefore, results in products with a weight ratio lacticacid:acetic acid below 3.0

Another aspect of our invention is a process for the preparation of ourfermented sour doughs. This process consists of the following steps:

stage I: making of a dough of 60-65 wt % of water, flour and/or bran andstarter material; fermenting the dough at 20°-40° C. during 8-24 hrsuntil pH is less than 4.2.

stage II: mixing of part of dough of stage I with flour and/or bran andwater until dough has water content of 58-63 wt %; fermenting this doughat 25°-40° C. during 2-12 hrs until pH=3.8-4.2

stage III: mixing of part of dough of stage II with flour and/or branwithout addition of water and fermenting this dough at 20°-40° C. during3-6 days until pH=3.8-4.0.

A free flowing fermented sour dough can be prepared by mixing of afermented sour dough with a water content of 25-32 wt % and a pH <4.2with a food acceptable salt, such as NaCl and a dried flour with a watercontent of 1-5 wt % in ratios of:

60-70 parts of sour dough of stage III

2-8 parts of the salt

22-38 parts of the dried flour

In this way a free-flowing fermented sour dough is obtained thatdisplays a water content of 20-25 wt %.

EXAMPLES

I. In stage I a composition was made, containing:

2.4 wt % Bocker ^(R) -starter material

19.8 wt % Rye-flour

15.0 wt % germ and bran of Rye

62.8 wt % of water

This composition was fermented at 30° C. for 9 hrs. Its titratableacidity was 17.5 and its pH=4.0.

In stage II a composition was made of:

12 wt % of product of stage I

20.6 wt % of Rye-flour

6.7 wt % of germ and bran of Rye

60.7 wt % of water

This mixture was fermented for 6 hrs at 30° C. Its titratable aciditywas 14.5 and its pH=4.0.

In stage III a composition was made of:

30.0 wt % of product of stage II

65.8 wt % of Rye-flour

4.2 wt % germ and bran of Rye

This mixture was fermented for 4.5 days at 35° to 25° C. (decreasingover the time period). Its titratable acidity was 30 and its pH=3.9.

II To the product of stage III above, salt was added, so that a mixtureof 93.7 wt % of product of stage III and 6.3 wt % of salt was obtained.

III A free-flowing dough powder was made by mixing of:

67 wt % of product of stage III

4.5 wt % NaCl

4.5 wt % dehydrated dextrose

24.0 wt % flour (with 3 wt % water)

The end-product contained 20.8 wt % of water.

IV.1 The lactic acid and acetic acid contents and its weight ratios weremeasured of:

A: a commercial, freeze-dried product: "Molda-Roggensauer"

B: a freeze-dried product made from the product of stage III mentionedabove

C: the product of example III above.

The results found were:

    ______________________________________                                        % lactic acid    % acet. acid                                                                            Ratio lac                                          ______________________________________                                        A     2.22           0.59      3.76                                           B     1.83           0.59      3.10                                           C     1.36           0.53      2.56                                           ______________________________________                                    

IV.2 A panel evaluation of the dry powders, using pair-comparison by 13panel members and 2 presentations, revealed that the aroma intensity ofthe products A, B and C displayed the following profile: C>A≈B.

We claim:
 1. Process for the preparation of a fermented, sour dough,wherein in a first stage a dough composition containing 60-65 wt % ofwater is made of: a) bran or flour or mixtures thereof; b) a sourstarter material and c) water; the dough composition is fermented at20°-40° C. during 8-24 hrs until the pH was dropped to less than 4.2;part of the dough of the first stage is mixed in a second stage withflour and/or bran and water until the dough displays a water content of58-63 wt %; the dough is fermented at 25°-40° C. during 2-12 hrs untilthe pH of the dough was 3.8-4.2 and part of the dough of stage two ismixed with flour and/or bran in a third stage, without the addition ofwater, whereupon the dough is fermented at 20°-40° C. during 3-6 daysuntil the pH of the dough is 3.8-4.0.